Flasher switch



May 14, 1963 G. R. LAWSON 3,089,934

FLASHER swucu Filed April 26, 1960 2 Sheets-Sheet 1 'NCREAS'NG MAGNETICFORCE vs GAP 4 CONTACT HOLDING FORGE i 0 SPRING FORCE vs GAP AT FORCEVARIOUS HOT WIRE TEMPERATURES f/n emon' 60 1 1?. Lad/sol? GAP 'r o gwAcT OPENING GAP INCREASE DU -4 GAP DUE TO CONTACT THK. /J' Z 1/778;

G. R. LAWSON FLASHER SWITCH May 14, 1963 2 Sheets-Sheet 2 Filed April26, 1960 f/n/e/rzar 605/6) ,6 Zea/s0 Afar/75y United States PatentOiiiice 3,.fid9,934i Patented May 14, 1963 3,089,934 FLAEEHER WHTCHGustaf R. Lawson, West Warwick, 13.1., assignor to General ElectricCompany, a corporation of New York Fiied Apr. 26, 19nd, Ser. No. 24,72416 Claims. (Cl. zen-422) The present invention relates to an electricaltiming switch of the type sometimes referred to as a flasher switch;more particularly, the invention relates to a timing switch to controlthe flashing of automobile turn indicator lights.

The present invention has as one of its objects to provide an improvedelectrical timing switch in which the timing cycle can be readilyadjusted.

Another object of the present invention is to provide an electricaltiming switch in which the switch contacts have snap action.

A further object of the invention is to provide an electrical timingswitch which may be readily assembled from a minimum number of parts.

Other objects of the invention will become apparent from a perusal ofthe following specification considered in conjunction with the attacheddrawing wherein FIG. 1 is a perspective view of a timing switch made inaccordance with this invention;

FIG. 2 is an exploded perspective View of the switch illustrated in FIG.1;

FIG. 3 is an enlarged view of a portion of the switch illustrating analternative structure;

FIG. 4 is a diagram of Force v. Armature Gap Distance illustrating thesnap action of the switch of this invention;

FIG. 5 is an alternative embodiment of the invention wherein a pilotlight circuit is included in the switch;

FIG. 6 is a bottom view of the embodiment of FIG. 5 showing the bladespacing;

FIG. 7 is a schematic diagram of a circuit including the switch of FIG.5;

FIG. 8 is an additional embodiment showing a switch which includes apilot light circuit;

FIG. 9 is a bottom view of the embodiment of PEG. 8 showing the contactblade spacing; and

FIG. 10 is a schematic diagram of a circuit including the switch of FIG.8.

Briefly stated, in accordance with one of its aspects, the timing switchof this invention comprises a nonconducting bar magnet, a first and asecond pole piece mounted on the opposite poles of the magnet, anarmature centrally mounted on the second pole piece, the armature havinga first leg disposed to make bridging engagement with the first polepiece and an oppositely extending second leg, and a resistance wireelectrically connected between the pole pieces and mechanicallyconnected between the second pole piece and theproiecting end of thesecond leg of the armature, the resistance wire when cold biasing thefirst leg of the armature out of contact with the first pole piecewhereby when the first and second pole pieces are connected in anelectric circuit the resistance wire is heated to expand and release thebias in the first armature leg enabling the magnet to attract the firstarmature leg to make contact with the first pole piece to establish acircuit which shunts the re istance wir Referring to the drawing, andparticularly to FIGS. 1 and 2, a very important element of the inventionconsists of a bar magnet 16, here shown in cylindrical form with thepoles located at the ends of the cylinder. Since this magnetelectrically insulates the other elements of the switch from each other,a preferred form the so-called ceramic magnet which consists of powderedmagnetic metal materials molded into a ceramic substance. Such magnetsare non-conducting, relatively inexpensive, and easily molded to anydesired shape. While they are preferred for use in this invention, it isunderstood that a conventional metal bar magnet can be used provided itis electrically insulated from the other elements of the structure.

Connected to one pole of the bar magnet 10 is a first pole piece 11which has a portion extending transversely outward from the magnet andwhich is then flared at the end. The opposite pole of the magnet is hasa second pole piece 12 extending transversely outward in the samedirection as the first pole piece and which likewise has a flared end.It will be noted that the flared portion of the second pole piece ismuch greater in area than the flared portion of the first pole piece.

A first terminal 13 is in engagement with the first pole piece 11 and asecond terminal 14 is in engagement with the second pole piece 12. Themagnet 1d, pole pieces 1.1 and 12, and terminals 13 and 14 comprise anassembly which is mounted upon a mounting base is composed of aninsulating material such as a molded phenolic. The assembly ismaintained on this mounting base as by a fastening screw 16. The firstterminal 13 has a portion extending through the mounting base 15 to forma contact blade 17, and the second terminal 14 has a portion extendingthrough the mounting base 15 to form a contact blade 18.

A resilient armature i9 is mounted upon the flare portion of the secondpole piece 12. The armature 19 has a first leg 21 disposed to engage theflared portion of the first pole piece 11 and an oppositely disposedsecond leg 22 having an end portion 23 bent over the magnet 10 at abouta -degree angle containing a notch 24. A portion of the material of thesecond leg 22 of the armature 19 has been removed to expose a centerfinger 25 and it is this finger 25 which mounts the armature on theflared portion of the second pole piece 12, as by welding. The use ofthe finger 25 as the mounting means increases the resilience of thearmature 19 so that it readily has motion with respect to the polepiece.

Connected between the terminals 13 and 14 is a resistance wire 26 havinga top portion 27 and a coiled portion 28 separated by a glass head 29positioned in the notch 24 of the armature 19. \Nhen cold, the top por-.tion 27 of the resistance wire 26 serves to bias the armature 19 out ofengagement with the first pole piece 11. The purpose of the coiledportion 28 is to provide easy means to vary the length of the resistancewire 26 in order to vary the heating time of the resistance wire 26 andthus the timing cycle of the switch.

The embodiment illustrated in FIG. 3 is similar to the embodiment ofFIGS. 1 and 2 except that an armature 31 is composed of rigid sheetmetal which fulcrums off of an end portion of the second pole piece 12.The rigidity extends only to the first leg 32 of the armature 31. Asecond leg 33 may be of resilient material as in the case of thearmature 19.

The embodiments of P168. 5 and 8 are similar to the embodiment of FIG. 1except that an additional contact 35 is present to provide a pilot lightcircuit. In both embodiments this contact 35 is substituted for the stopmember 34 of FIGS. 13. The contact 35 terminates in a third contactblade as through which connection to an external pilot circuit is madein the FIG. 5 embodiment.

In the embodiments of FIGS. 1-3 the contact blades 17 and 18 are spaced90' degrees from each other. In order to permit the contact bladeconfiguration to conform to established standards of use, thethree-blade switches of FIGS. 5 and 8 have two blades oppositelydisposed to each other and the third contact blade positioned at rightangles thereto.

The operation of the switch embodiments of FIGS. 13 is substantially thesame and will now be described. The switch is piugged into a turnindicator circuit of an 3 automobile by means of the contact blades 17and 1'3. :When the turn indicator switch is now operated, a circuit isestablished from the first terminal 13 through the resistance wire 26and the second terminal M. This also f-completes a circuit to operatethe turn indicator lights of the automobile but due to the highresistance of the resistance wire 26, the lights are not operatedsufficiently to be visible. However, the resistance wire 26 at onceheats up and in so doing the top portion 27 expands sufficiently torelease its bias holding the first leg of the armature out of engagementwith the first pole piece. Magnetic attraction then pulls the first legof the armature into engagement with the first pole piece and thisest-ablishes an electrical circuit from the first terminal 13, throughthe first pole piece 11, first leg of the armature, second pole piece12, and second terminal 14 which shunts out the resistance wire 26. Atonce, the turn indicator lights of the automobile come on full and theresistance wire 26 beings to cool. When it has cooled sufiiciently, itcontracts to restore the first leg of the armature to its initialposition out of engagement with the first pole piece ill and the cycleis now ready to commence once again. The length and diameter of theresistance wire 25 may readily be adjusted to provide for flashing ofthe turn indicator lights one to two cycles per second.

As iilustnated in FIG. 7, the operation of the switch "9f the HS.embodnnent is the same as that described above for FIGS. 1-3 except thata pilot lamp 357 is energized as soon as the turn indicator circuit ofthe automobile is closcd. At the same time, the resistance wire 26 isenergized through a circuit which includes signal lamps 38 but thesignal lamps do not emit a significant quantity of light due to thevoltage drop across the resistance wire 26. However, the wire 26 heatsup and lengthens to release the armature 19 which makes contact with thepole piece 11 to shunt the wire 26 which then cools and contracts torestore the switch to the position illustrated in FIG. 5.

As shown in FIG. 10, the embodiment of FIG. 8 has the portion 27 of theresistance wire in series with the terminal 14. The signal lamps 38 inthis embodiment are energized when the armature it? is in the positionillustrated in FIG. 7 and the pilot lamp 37 is energized when thearmature i9 is drawn to the second pole piece 12. The wire 27 in thisembodiment is given a low resistance and this does away with thenecessity of the glass bead 29 but makes it necessary to includeinsulating washers 39 and 41 to insulate the terminals from the polepieces. When the automobile turn signal switch is operated, the signallamps 38 come on full brilliance and the wire 26 heats from the fullload current. This heat lengthens the wire 26 which relaxes its hold onthe armature 19 to enable it to be drawn into contact with the firstpole piece 11. This breaks the circuit to the signal lamps 38 and closesthe circuit energizing the pilot lamp 37 which goes on. While the wire26 is also in the pilot lamp circuit, the current drawn by the pilotlamp is so small that the wire 26 cools and contracts to draw thearmature 19 away from the pole piece 11 and into engagement with thecontact 35 to restore the switch to the position illustrated in FIG. 7.

It has previously been mentioned that the switch of this invention hassnap actiona very desirable feature which lengthens the life of thecontacts. This action will be described with reference to FIG. 4. Thesnap action of the switch is accounted for by the difierence in behaviorof the Spring force of the resilient armature 19 :and the magneticforce. The magnetic force is inversely proportional to the square of thedistance between the pole piece and the armature. The spring force ofthe resilient armature, on the other hand, varies linearly in proportionto the strain placed upon it by the wire provided the range of thisstrain is not too great. Thus, it is possible to correlate the contactgap distance (distance between the first leg of the armature and firstpole piece), magnetic strength, and spring gradient such that thearmature connect be held suspended in the gap but will always move intoengagement with the first pole piece or out of engagement to a stop 34on the mounting base 15 depending upon how the armature i9 is flexed bythe resistance wire 26.

in FIG. 4, if the straight sloping lines become steeper than the curveat the point of operati0n-a condition brought about when the spring istoo stifior if the curve becomes less steep than the sloping lines-acondition brought about when the magnetic field is too wealrthe switchwill not operate with a snap action. Therefore, the gap, magnetic field,armature stiffness, and resistance wire tension must be correlated togive the force conditions illustrated at a, b, c, and d of FIG. 4. Theforce illustrated at a in FIG. 4 is the contraction of the resistancewire upon cooling. At 17, the contacts snap open. At c, the resistancewire has expanded upon heating to release its tension tending to holdthe contacts in open position. At d, the magnetic attraction has snappedthe contacts into closed position.

While the invention has been described with reference to certainspecific embodiments, it is obvious that there are a number of possiblevariations which would still fall within the spirit of the invention.Therefore, the invention is properly limited in scope only as may benecessitated by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electrical timing switch comprising a non-conducting bar magnet, afirst and a second pole piece mounted on the opposite poles of saidmagnet, an armature centrally mounted on said second pole piece, saidarmature having a first leg disposed to make bridging engagement withsaid first pole piece and an oppositely ex tending second leg, and aresistance wire electrically connected between said pole pieces andmechanically connected between said second pole piece and the projectingend of the second leg of said armature, said resistance Wire when coldbiasing the first leg of said armature out of contact with said firstpole piece whereby when said first and second pole pieces are connectedin an electric circuit said resistance wire is lengthened by heating torelease the bias on said first armature leg enabling said magnet toattract said first armature leg to make contact with said first polepiece to establish an electrical circuit which shunts said resistancewire.

2. An electrical timing switch as claimed in claim 1 wherein theresistance wire has a taut portion and a coiled portion, the length ofthe coiled portion being adjustable.

3. An electrical timing switch as claimed in claim 2 wherein the polepieces are flared outward and the second leg of the armature has anotched end portion bent at an angle of about toward the magnet.

4. An electrical timing switch as claimed in claim 3 wherein the tautportion of the resistance wire is separated from the coiled portion by aglass bead positioned in the notched portion of the armature second leg.

5. An electrical timing switch as claimed in claim 1 wherein thearmature is resilient and fixedly mounted on the second pole piece.

6. An electrical timing switch as claimed in claim 1 wherein thearmature is rigid and fulcrum-mounted on the second pole piece.

7. An electrical timing switch comprising a non-conducting bar magnet, afirst conducting pole piece attached to one pole of said magnet and asecond conducting pole piece attached to the other pole of said magnet,a terminal mounted on each pole piece, a mounting base of insulatingmaterial on which said magnet, pole pieces, and terminals are mounted,each terminal having a contact blade portion extending through saidmounting base, an armature centrally mounted on said second pole piece,said armature having a first leg disposed to make engagement with saidfirst pole piece and an oppositely disposed second leg, and a resistancewire insulatingly connected to the end of said second armature leg andextending to the terminal adjacent said second pole piece, saidresistance wire when cold biasing said armature out of engagement withsaid first pole piece and releasing said armature when heated wherebysaid armature engages said first pole piece to close a circuit shuntingsaid resistance wire.

8. An electrical timing switch as claimed in claim 7 wherein thearmature is resilient and fixedly mounted on the second pole piece.

9. An electrical timing switch as claimed in claim 7 wherein thearmature is rigid and fulcrum-mounted on the second pole piece.

10. An electrical timing switch as claimed in claim 7 wherein the polepieces are flared and the second leg of the armature has a notched endportion bent at an angle of about 90 toward the magnet.

11. An electrical timing switch as claimed in claim 10 wherein theresistance wire has a taut portion and a coiled portion separated by aglass bead and the said glass bead is positioned in the notched portionof the second leg of the armature.

12. An electrical timing switch comprising: a mounting base ofinsulating material; an assembly comprising a nonconducting bar magnet,a first pole piece, an oppositely disposed second pole piece, a firstterminal attached to said first pole piece, and a second terminal attached to said second pole piece mounted on said mounting base, saidpole pieces extending transversely across said bar magnet and beingflared at one end; an armature mounted on the flared portion of saidsecond pole piece, said armature having a first leg disposed to engagethe flared portion of said first pole piece and an oppositely disposedsecond leg notched at the end and folded at said end in the direction ofsaid magnet; a resistance wire connected between the end of said secondleg of said armature and said second terminal for biasing said armatureto a position out of engagement with said first pole piece; and a glassbead on said resistance wire for positioning said wire in the notch atthe end of the second leg of said armature, said glass bead dividingsaid resistance wire into a taut portion and a coiled portion.

13. An electrical timing switch as claimed in claim 12 wherein the firstand second terminals include Contact blades which extend throughapertures in the mounting base.

14. An electrical timing switch as claimed in claim 12 wherein thearmature is resilient and fixedly mounted on the second pole piece.

15. An electrical timing switch as claimed in claim 12 wherein thearmature is rigid and fulcrum-mounted on the second pole piece.

16. An electrical timing switch comprising a non conducting bar magnet,a first and a second pole piece mounted on opposite poles of saidmagnet, an armature centrally mounted on said second pole piece, saidarmature having a first leg disposed to make bridging engagement withsaid first pole piece and an oppositely extending second leg, a contactspaced from said first pole piece, said contact being engageable by saidfirst leg of said armature, and a resistance wire electrically connectedbetween said pole pieces and mechanically connected between said secondpole piece and the projecting end of the second leg of said armature,said resistance wire when cold biasing the first leg of said armatureout of engagement with said first pole piece and in engagement with saidcontact whereby when said first and second pole pieces are connected inan electric circuit said resistance wire is lengthened by heating torelease the bias on said first armature leg enabling said magnet toattract said first armature leg to make contact with said first polepiece to establish an electrical circuit which shunts said resistancewire.

References Cited in the file of this patent UNITED STATES PATENTS2,103,276 Schmidinger Dec. 28, 1937 2,172,666 Michel Sept. 12, 19392,639,345 Sitzer May 19, 1953 2,715,187 Schmidinger Aug. 9, 19552,735,967 Lew'us Feb. 21, 1956 2,747,052 Blume May 22, 1956 2,749,404Flubacker June 5, 1956

1. AN ELECTRICAL TIMING SWITCH COMPRISING A NON-CONDUCTING BAR MAGNET, AFIRST AND A SECOND POLE PIECE MOUNTED ON THE OPPOSITE POLES OF SAIDMAGNET, AN ARMATURE CENTRALLY MOUNTED ON SAID SECOND POLE PIECE, SAIDARMATURE HAVING A FIRST LEG DISPOSED TO MAKE BRIDGING ENGAGEMENT WITHSAID FIRST POLE PIECE AND AN OPPOSITELY EXTENDING SECOND LEG, AND ARESISTANCE WIRE ELECTRICALLY CONNECTED BETWEEN SAID POLE PIECES ANDMECHANICALLY CONNECTED BETWEEN SAID SECOND POLE PIECE AND THE PROJECTINGEND OF THE SECOND LEG OF SAID ARMATURE, SAID RESISTANCE WIRE WHEN COLDBIASING THE FIRST LEG OF SAID ARMATURE OUT OF CONTACT WITH SAID FIRSTPOLE PIECE WHEREBY WHEN SAID FIRST AND SECOND POLE PIECES ARE CONNECTEDIN AN ELECTRIC CIRCUIT SAID RESISTANCE WIRE IS LENGTHENED BY HEATING TORELEASE THE BIAS ON SAID FIRST ARMATURE LEG ENABLING SAID MAGNET TOATTRACT SAID FIRST ARMATURE LEG TO MAKE CONTACT WITH SAID FIRST POLEPIECE TO ESTABLISH AN ELECTRICAL CIRCUIT WHICH SHUNTS SAID RESISTANCEWIRE.